“January is always the busiest month for us,” says Robby Huang, co-owner of Revel Fitness, a Zumba studio in Carmel, Ind. “We find a lot of people make New Year’s resolutions and they really stick to them really well.”

The influx in customers doesn’t make it harder to fit clients in at Revel Fitness because they don’t use equipment. Huang says the classes just get bigger. Their busy season tends to last through March and April.

One damper on this year’s January boom for Huang? The snow storm that’s shut down much of the Midwest. Revel studio is closed today but Huang hopes to be open again soon.